This invention relates to tonneau covers for the cargo compartment of pickup trucks.
Pickup trucks have rectangular shaped beds at the rear of the vehicle, generally with a pivoting tailgate that pivots downwardly and in a rearward direction to a flat, horizontal plane that is generally in the same plane as the floor of the bed. Pickup trucks are used for numerous purposes for hauling all types of articles, that vary in size, shape and weight. At times it is beneficial that the bed be covered to protect the articles being transported.
Various covers have been used in the past. There are essentially two types of tonneau covers: flexible and rigid. One type is comprised of flexible covers including canvas, other fabrics, and flexible vinyl covers. The flexible cover is secured to the pickup truck by ropes, flexible cords, and other straps that are secured by hooks, ties, snaps, and other fasteners or attached to frames that are mounted on the pickup truck. A disadvantage of these types of covers is that they are extremely time consuming to put in place and secure to the truck, with a similar amount of time required to remove them. Due to the flexible characteristics of the cover, they can allow water to pool in low spots, rather than run off and onto the ground. Due to their lack of structural strength, they do not permit the user to install other items, such as racks, onto the flexible cover and provide minimal security.
As an alternative to a flexible cover, a second type of tonneau cover has gained popularity. These are rigid covers comprised of one piece rigid covers and multi-piece sectional rigid covers. Fiberglass, metal, and rigid plastic covers have been introduced and are usually pivotally connected to a frame or brackets mounted to the front and sides of the pickup truck bed. These allow the user to raise the cover from the rear of the bed, place the items in the bed, and lower the cover to protect the items. Generally hinges or other connectors are used to connect the cover to the truck bed or truck body. These connections are not readily or easily removed if the cover is to be removed for additional storage space. A disadvantage of these types of covers is their weight and the durability of the aesthetics of their top surface. Another disadvantage is complexity of installing and aligning the frame or brackets to the pickup truck bed.
Many of the rigid covers are made of two joined pieces or shells of plastic, such as illustrated in U.S. Pat. No. 6,547,310 issued to Myers. This patent illustrates a plastic cover that has supporting or reinforcing ribs placed across the bottom side of the cover. This design has several disadvantages that are found in all covers using a supporting ribbed structure. One disadvantage is that when a user wants to add an option or attachment to the cover, the mounting is made more difficult due to the rib structure. In all other areas of the cover, the thickness of the sheet precludes making a strong and solid attachment. Depending on where the attachment is made, a bolt, screw, or other fastener may be passing through only a thin portion of the cover or could be passing through the top surface and the generally hollow rib structure. Thus, the user is restricted to where he or she can mount the accessory.
Another disadvantage of this type of plastic tonneau construction is that it requires some form of reinforcing rib on the underside of the cover for structural rigidity. An example of this is seen in U.S. Pat. No. 6,340,194 issued to Muirhead et al. This patent illustrates a cover made from two sheets of heat deformable plastic material instead of using fiberglass reinforced plastic. The bottom panel has reinforcing ribs for additional strength. This reinforcing structure creates lines (“witness marks”) that are easily or at least partially visible to the observer on the top side of the cover. In extreme temperatures or when condensate forms due to humidity and temperature changes, the lines on the cover are even more obvious.
This type of plastic tonneau also has a non uniform, and generally not even under surface due to the reinforcing rib structure. If the underside is not even, it makes it difficult to satisfactorily attach carpet or other sheet materials to the under or bottom surface and also makes it difficult to mount accessories. These materials are preferably maintained flat against the underside of the cover for appearance reasons.
Yet another disadvantage of the two piece ribbed designs that have large areas between places where the two pieces are bonded together is that differential thermal expansion and contraction on the top cover piece often causes cracking, peeling, bowing, or other deformation of other surface imperfections, of paint applied to the top surface. This construction has large areas on the top shell that are not rigidly bonded to the bottom shell. The non-bonded areas of the top shell thermally expand and contract at a different rate than the areas of the top shell that are bonded to the bottom shell. This thermal expansion and contraction result in cracking and bowing which lead to cracking and peeling of the paint on the top surface of the top shell and other undesirable surface effects.